Transpile license-expression into javascript - Python3-only

[alisianoi]

This is a long running PR that will capture progress on transpiling license-expression into javascript with Transcrypt. The very first problem was to bundle a vendored version of Transcrypt as a development dependency: a) Transcrypt does not build wheels by default and b) not all changes that are required have been accepted (and they are not instantly accepted, it takes a while).

So, I am bundling a custom wheel with the changes that I need with the first commit. Next order of business: where to put the transpilation script (boolean.py currently has etc/transpile.py as the script that powers transpilation).

Update: relevant license-expression issue about online tool: #18

[pombredanne]

@all3fox could it therefore make sense to move or fork your transcrypt fork with patches as an org-level repo too?

[alisianoi]

Yes, maybe it is worth to just move my all3fox/Transcrypt to nexB/Transcrypt and give me some modification rights?

[pombredanne]

@all3fox sure, let's do this tomorrow

[pombredanne]

This get transcrypt instead directly from a wheel path.... but this also requires mypy? now by default configure work on Python 2.... I am not sure I tested this on Python 3?

[alisianoi]

Thanks for help, I've added PyYAML and transpile.py. Now, when I do:

./configure etc/conf/dev/transpile
./bin/activate
./bin/python ./transpile/transpile.py

Transcrypt works but for some reason does not pick up src/license_expression/__init__.py and instead picks up nothing and generates an "empty" __init__.js in:

lib/python3.6/site-packages/transcrypt/modules/__javascript__/__init__.js (it contains just boilerplate for Transcrypt base modules but nothing from license-expression). I am investigating what's going on.

[pombredanne]

if it helps temporarily to rename __init__.py to license_expression to go over that hump, do it! remember let's not get mundane stuff go in your way...

[alisianoi]

Ok, at this point ./bin/python transpile/transpile.py chokes because it needs a transcrypt-friendly version of boolean.py. For some reason, creating a wheel out of the transpile branch of boolean.py, copying it over to license-expression/thirdparty/prod and reassembling the virtual environment with:

deactivate
./configure clean
./configure clean etc/conf/dev/transpile
./configure
./configure etc/conf/dev/transpile
./bin/activate
./bin/python transpile/tranpile.py

does not do the trick. That's weird but a more reliable workaround is to manually install required branch of boolean.py after the ./configure etc/conf/dev/transpile step: ./bin/pip install -e ../boolean.py

[pombredanne]

That's weird but a more reliable workaround is to manually install required branch of boolean.py after the ./configure etc/conf/dev/transpile step: ./bin/pip install -e ../boolean.py

that works too.

[alisianoi]

As I've mentioned on gitter, the Internal Error: too much recursion was caused by a chain of exceptions that got triggered because an if statement branched into the wrong branch. Turns out that I missed a transpilation switch/pragma mechanism pointed out to me here. I will be taking a look at it tomorrow and potentially using it instead of transcrypt_true hack-y function.

Right now I am facing an ReferenceError: py_TypeError is not defined when I try these commands:

let song = __init__.Licensing()
let expr = song.parse("MIT or GPL")

I've seen this error at this exact step before in boolean.py: that was caused by poor iteration over the loop and was fixed by using the -e 6 switch. This time, however, the reason is different and I have not figured it out yet. My best guess: between the Licensing.parse() call and the BooleanAlgebra.parse() call the string "MIT or GPL" magically turns into an empty array (and then BooleanAlgebra.parse() freaks out because it wants a string). However, I've not yet figured out why.

While I was figuring out the cause for a py_TypeError is not defined, I tried to hot-patch Transcrypt to contain that particular type of error: https://github.com/all3fox/Transcrypt/tree/type-error For some reason it did not work. Anyway, when I figure out the problem from the previous paragraph, having a TypeError would not be top priority.

[pombredanne]

I just rebased your branch and pushed this as alisianoi-transpile here. I could have but did not dare force push to your repo after the rebase! I might merge this rebased branch instead

[pombredanne]

For reference, this depends on bastikr/boolean.py#72
And when merged we will need to start having a Python2-only maintenance branch as this branch will only support Python3